Cranes, as devices for lifting weights and having a function of automatical movement, are widely applied in the field of engineering machinery. Among them, a single cylinder bolt system is a device built into a telescopic boom of the crane to assist the telescopic cylinder to realize the telescopic function of the telescopic boom of the crane. A single cylinder bolt system mainly consists of a telescopic boom and a cylinder, wherein main functional components for a hoist boom to realize extension and contraction include a cylinder head, a cylinder head body, a slide rail, a rail bracket, a boom pin, a cylinder pin, a dovetail groove, a driving cylinder, a detection switch and other auxiliary facilities.
The cylinder head is in a certain position of a cylinder barrel or a piston rod of the telescopic cylinder for controlling coupling and decoupling between the telescopic cylinder and the telescopic boom and between telescopic booms. The cylinder head mainly comprises a cylinder head body, a boom pin driving device, a cylinder pin driving device, a driving cylinder, a position detection block and so on. The cylinder head body is directly connected to the cylinder, for assembling the boom pin driving device, the cylinder pin driving device and carriers of other components, which is a major component of the cylinder head.
As a constituent part of the telescopic cylinder, the slide rail is assembled on the telescopic cylinder. It has a function of maintaining the position of the telescopic cylinder in the hoist boom slide and preventing the telescopic cylinder from spinning or flexing in the hoist boom. The rail bracket is also a constituent part of the telescopic cylinder, for assembling the slide rail, and it is generally welded on the cylinder barrel along the axial direction, and one telescopic cylinder has a number of rail brackets. The cylinder pin is a pin on the cylinder, which has a function of locking the cylinder and the telescopic boom together. In existing products, each cylinder head generally has two or four cylinder pins. The boom pin is a pin on the telescopic boom, which has a function of locking telescopic booms together. In existing products, each cylinder head generally has one or two boom pins. The cylinder pin rail is mounted within the cylinder head, whose structure is provided with a slide, along which the cylinder pin moves to realize telescopic motion of the cylinder pin. The boom pin rail is mounted within the cylinder head, whose structure is provided with a slide, along which the boom pin moves to realize unlocking motion of boom pin. The driving cylinder is an actuator for realizing motion of the boom pin and the cylinder pin.
Existing single-cylinder-bolt cylinder head bodies are all in one piece, forged or welded, which are inserted from one end of the cylinder during assembling of the cylinder. Ordinary cylinder head bodies are assembled on the piston rod, and they need to be inserted into the piston rod to be assembled. Assembling of multi-cylinder-head cylinders is more cumbersome. For a multi-cylinder-head cylinder, the cylinder head body needs to be assembled on the cylinder barrel. The cylinder barrel of the telescopic cylinder is welded with a flange connected to an end face flange of the cylinder body, and the cylinder barrel is assembled or welded with a rail bracket, so that the cylinder head body must be inserted into the cylinder barrel when assembled, then the cylinder head body and the flange are connected, then the rail bracket is assembled or welded, the slide rail is assembled on the rail bracket, and assembling of the cylinder is finished. In practical production process, cylinder heads may not be supplied in time, causing failure in sequential mounting. Moreover, dismounting is inconvenient during maintenance of the cylinder head body. If the slide rail and the cylinder barrel are connected in an assembling way, dismounting is more convenient, but it is still time-consuming. Generally the rail bracket and the cylinder barrel are welded together, because in this way, connection of the slide rail and the cylinder is more firm, which results in that the cylinder head body cannot be dismounted for maintenance.
FIG. 1 is a schematic view of the structure of an existing single-cylinder-bolt cylinder head body mounted on a telescopic cylinder. The cylinder head body a3 mounted on the cylinder barrel a1 is inserted from the bottom of the cylinder. Then the end face flange a4 of the cylinder head body a3 is connected to the flange bolt a5 welded on the cylinder barrel. Then the rail bracket a6 is assembled or welded, and then the slide rail a2 is assembled, this assembling sequence cannot be reversed. The cylinder head body a8 assembled on the cylinder rod a9 should be inserted by the cylinder rod a9 before the cylinder rod a9 is mounted in the cylinder barrel a1, and then connected to the cylinder barrel a1, such mounting sequence cannot be reversed, either, or it cannot be assembled because of influence of the end face flange a7 and the earring a10.
Therefore, existing cylinder head bodies have at least the following technical defects:
First, assembling is not flexible. In the telescopic cylinder, because of influence of the rail bracket, the flange, the earring, the valve seat and so on, the cylinder head body can only be inserted along the axial direction of one end of the cylinder barrel or the cylinder rod, i.e., the cylinder head body can only be inserted along the axial direction so as to be assembled.
Second, production efficiency is low. Affected by the assembling sequence, one cannot assemble other components first and assemble the cylinder head body at last. Insufficient supply of cylinder head bodies affects assembling of other components.
Third, maintenance is difficult. Both axial sides of the cylinder head body assembled on the cylinder barrel are welded or assembled with components besieging the cylinder head body, making it enclosed and impossible or inconvenient to dismount. For maintenance of the cylinder head assembled on the cylinder rod, the cylinder rod must be extracted first.